The present invention relates in general to an automatic brake hold wherein application of the brakes can be maintained automatically after a vehicle operator brakes the vehicle to a stop, and, more specifically, to an automatic brake hold system without interference with low speed maneuverability.
An automatic braking feature for motor vehicles has been introduced known by the terms automatic vehicle hold (AVH), automatic brake hold, or brake autohold. A driver-controlled switch determines whether the feature is active. When active, a controller monitors vehicle movement. When the vehicle brakes to a stop (with the feature active) and the driver releases the brake pedal, brake pressure is automatically held to keep the vehicle at a stop. When the driver takes action to resume motion (e.g., pressing the accelerator pedal), the brake torque is released so that full control is restored to the driver. Driver fatigue is reduced since the need for continued pressure on the brake pedal during a long stop is eliminated.
During parallel parking and other low-speed maneuvers, a driver may take advantage of the creep of the vehicle that occurs when an automatic transmission vehicle is in gear and the brake is released without requiring any activation of the accelerator pedal (i.e., at idle). For example, the vehicle may move back and forth repeatedly to complete a parallel parking maneuver. When changing direction, a low-speed creep using only the brake pedal may be preferable to using the accelerator pedal in order to move the vehicle a short distance. An operator switch is provided which allows the driver to cancel the brake autohold function any time that it interferes with the low-speed maneuver. However, it would be desirable to automatically control the brake autohold feature in a way that avoids interfering with these low-speed maneuvers without requiring driver intervention.